A REVIEW ON FLOW VISUALIZATION AND TRANSPORT PHENOMENA OVER A SLOT-PERFORATED FLAT SURFACE BETWEEN TWO PARALLEL PLATES

摘要

A theoretical and experimental study is performed to investigate unsteady, two-dimensional, incompressible thermal-fluid flow over both sides of a slot-perforated flat surface, which is placed in a two-dimensional channel. The governing boundary-layer equations are discretized by means of a finite-difference technique to determine streamwise and transverse velocity components. The roles of both the Reynolds number and the ratio of the slot width, d, to the plate thickness, 5, on the velocity and thermal fields are disclosed. It is found from the study that: (1) at a small value of Re and/or d/b,flow and thermal fields over the slot exhibit no timewise variation; (2) when Re and d/ b exceed certain values, an alternate crossing of flow from one side of the plate to the other occurs across the slot; (3) the alternating change in the fluid flow disturbs the thermal boundary layer formed along the plate and induces mixing of the upper and lower streams of the plate downstream from the slot, resulting in an amplification of heat transfer performance; and (4) heat transfer rate at the plate is affected by a combination of Re and d/δ. These results in the velocity field are confirmed by the flow visualization using ion-exchange resins.